1. Field
This disclosure relates generally to semiconductor memories, and more specifically, to a flash memory having P-type split gate memory cells and method of operation.
2. Related Art
There are various types of non-volatile memories. One type of flash memory uses a split-gate memory cell having a floating gate for charge storage, a select gate, and a control gate. The split-gate memory cell is also commonly known as a 1.5 T cell. In the split-gate memory cell, the select gate and the control gate may be separated by only a few hundred angstroms, making the split-gate cell substantially smaller than a 2 T cell that generally has wider spacing between the select gate and control gate. A split-gate memory cell can be categorized as having either an N-type or P-type channel region. The P-channel split-gate memory cell has certain disadvantages when compared to an N-channel cell. For example, a program window between erased and programmed voltages may be relatively small. Also, operating voltages of the P-channel cell may be relatively high. In addition, erase times may be relatively long compared to an N-channel split-gate cell. However, it may be desirable to use P-channel split-gate cells in some integrated circuit designs.
Therefore, what is needed is a P-channel split-gate memory cell that solves the above problems.